Apparatus for heating a green tire

ABSTRACT

An apparatus for effectively heating a green tire generates heat to a metal member embedded therein using electromagnetic induction, to complete a heating formation of a green tire in a sufficiently short time. Particularly, in the thick portion of the green tire which is hard to heat, the efficiency of heat generation due to electromagnetic induction is increased by effectively concentrating a high frequency magnetic field on the metal member embedded therein. The apparatus for heating a green tire includes a local heating coil for forming a high frequency magnetic field along a portion of extending direction of a metal member, a high frequency power supply for supplying high frequency power to the local heating coil, and a mechanism for moving the local heating coil relatively in the extending direction of the metal member.

The present application is a Divisional of U.S. patent application Ser.No. 09/902,697, now U.S. Pat. No. 6,818,872 filed on Jul. 12, 2001, theentire contents of which are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. (Field of the Invention)

The present invention relates to an apparatus for heating a green tireduring vulcanizing process or the preceding process thereof.

2. (Description of the Related Art)

Conventionally, a green tire formed by a forming machine is kept in arack of keeping place set inside a building of a vulcanizing facilitiesand the like under room temperature conditions, and is taken from therack to convey to a vulcanizing machine based on a production plan. Ifthe green tire is carried in the vulcanizing machine, for example in abladder type vulcanizing machine, the green tire is loaded into a moldby clamping the mold, and then a heat medium under high temperature andhigh pressure is supplied in a bladder inserted into a tire hole, sothat the bladder is extended to be close to an inner wall surface of thetire. And, by heating the inner wall surface of the tire whilepressurizing it in a mold direction via the bladder, a tire groove ofthe mole is formed in a tread portion of the green tire. Also, byheating the green tire from the inside and the outside using the heatedmold and the bladder contacting to the heat medium of high temperature,to rise temperature of the green tire up to a vulcanizing initiationtemperature (at least 100˜120° C.) early, it is possible to complete avulcanizing process in a short time.

However, as above-described prior art, if the green tire is kept for along time under room temperature conditions, then the green tire becomesthe temperature near room temperature, for example 25° C., therefore itis necessary to rise the temperature of the green tire from roomtemperature to initial temperature of vulcanizing when vulcanizingformation the green tire in the vulcanizing machine. In the prior art,as described above, although the vulcanizing process is completed in ashort time by heating the green tire from the inside and the outsideusing the mold and the bladder, but the green tire has a rubber of whichheat transfer ratio is low as a main component, therefore thoughtemperature of a surface of the green tire is raised in a short time,the temperature rising of inner center particularly in a large thicknessportion of the tread having large thickness and bead portion isremarkably delayed. Accordingly, vulcanizing process must be continueduntil temperature of the inside of the green tire is raised to completethe vulcanization, even when vulcanization of the surface side of thegreen tire is completed, therefore there is a problem that thevulcanizing process could not completed in a sufficiently short time.

Also, a method of irradiating a micro wave to a green tire when thegreen tire is kept, for preheating the green tire before vulcanizingprocess is adopted. But in this method, the macro wave preheats (heat)mainly the surface side of the green tire and the inside in which thetemperature rising is most delayed upon vulcanization, can not bepreheated sufficiently, therefore it is not a fundamental solution forcompleting vulcanizing process in a short time.

Furthermore, such problems are caused in a various type of a vulcanizingmachine such a bladder type, a bladder-less type etc., and particularlyin the bladder type vulcanizing machine, the problems become moreserious since the bladder itself is formed of rubber having low heatconduction ratio.

Also, as disclosed in Japanese Patent Laid-Open No. Hei 7-96525, thereis known a technique that a green tire comprising a bead and belt layerof conductive material is heated from the inside, by generating amagnetic field in the portion of the bead and belt layer to induceover-current due to electromagnetic induction thereby generating heat.However, the study has not been made for how to constitute an apparatusfor efficiently heating when adopting the heating method to thevulcanization of green tire.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide anapparatus for effectively heating a green tire using a heating method bymeans of electromagnetic induction, thereby completing a heatingformation of a green tire in a sufficiently short time.

To solve the above problem, according to one aspect of the presentinvention, there is provided an apparatus for heating a green tire bygenerating heat to a metal member embedded in the green tire usingelectromagnetic induction, comprising: a local heating coil for forminghigh frequency magnetic field along a portion of an extending directionof said metal member; a high frequency power supply for supplying highfrequency power to said local heating coil; and moving means for movingsaid local heating coil relatively in the extending direction of saidmetal member.

With above construction, since the local heating coil forms highfrequency magnetic field along a portion of extending direction of saidmetal member, heat generation effect on the portion of the metal memberis increased. At this time, it is possible to heat the whole metalmember efficiently, by relatively moving the local heating coil and saidmetal member.

Here, said local heating coil can form high frequency magnetic fieldalong a portion of facial direction of a ring-belt-shaped metal memberembedded in a tread portion of said green tire, or can form highfrequency magnetic field along a portion of peripheral direction of awire-ring-shaped metal member embedded in a tread portion of said greentire.

Also, said local heating coil can comprise a center core, a side coreand a coil, and at least one of said center core, said core and saidcoil can have a deformed portion, and said deformed portion may beformed so as to concentrate high frequency magnetic field to said treadportion or a shoulder portion continued from said tread portion.

In some cases, the shoulder portion is positioned at the both ends ofthe ring-belt-shaped metal member and curved in a width direction, orthickness of the shoulder portion is thicker than that of the treadportion. In such cases, heating to the shoulder portion becomes morenecessary. According to the above construction, the deformed portionthereof concentrates magnetic flux on the both ends of a width directionof the ring-belt-shaped metal member positioned at the shoulder portion,so that it is possible to increase heat generation efficiency at theseportions.

Said center core can be formed as a curved surface or stepped shape soas to follow the periphery of said green tire.

With above construction, since the center core is formed as a curvedsurface or stepped shape corresponding to R shape of peripheraldirection of the green tire, the magnetic flux is easily formed alongthe peripheral direction of the ring-belt-shaped metal member and heatgeneration efficiency of the ring-belt-shaped metal member can beimproved.

Said local heating coil can be installed apart in a width direction ofsaid tread portion and can be constructed to have installation intervalvariable in response to the green tire size.

With above construction, the magnetic flux can be formed in the wholewidth direction, by adjusting the installation interval of said localheating coil in response to size of width direction of thering-belt-shaped metal member.

Said local heating coil can be constructed to comprise a spiral coil anda core arranged on a side of said spiral coil.

With above construction, high frequency magnetic field is formed alongperipheral direction of the wire-ling-shaped metal member, so that thewire-ring-shaped metal member is heated efficiently.

Said spiral coil can have an approximately elliptical shape followingsaid wire-ring-shaped metal member and said core may have a square shapefollowing said wire-ring-shaped metal member.

With above construction, the spiral coil having an approximatelyelliptical shape forms magnetic field efficiently following thewire-ling-shaped metal member.

Said moving means can be a rotational driving mechanism for rotatingsaid green tire about a center axis thereof.

With above construction, it is possible to realize uniform heating ofthe whole metal member more efficiently.

Furthermore, said local heating coil can be placed between a pair ofgreen tires so that it can heat said pair of green tire simultaneously.

Said local heating coil can be provided so as to heat one green tire,and a ferrite core can be disposed opposite to said green tire withrespect to said local heating coil.

With above construction, magnetic flux opposite to the green tire isconverged so that heating efficiency can be increased.

The apparatus can further comprise an auxiliary core, and said auxiliarycore can be disposed so as to raise the density of high frequencymagnetic field of said shoulder portion.

With above construction, magnetic flux is concentrated on both ends ofwidth direction of the ring-belt-shaped metal member positioned at theshoulder portion, so that heating efficiency at this portion can beincreased.

According to other aspect of the present invention, there is provided,an apparatus for heating a green tire by generating heat to a metalmember embedded in the green tire using electromagnetic induction,comprising: a heating coil for forming high frequency magnetic fieldalong a portion of an extending direction of said metal member, saidheating coil being constructed to be insertable through a tire hole ofsaid green tire; and a high frequency power supply for supplying highfrequency power to said heating coil, wherein said heating coil isdisposed so that both ends thereof are positioned in the vicinity ofboth bead portions of said green tire.

With above construction, high frequency magnetic field produced from acolumnar heating coil inserted through the tire hole induction-heats ametal member of the tread portion and a metal member of the beadportion, so that it is possible to sufficiently perform preheatingparticularly, of the tire inside of tread portion and bead portionhaving large thickness where temperature rising is delayed.Additionally, since the metal member of the tread portion and beadportion can be induction-heated using only one columnar heating coil, itis possible to save the cost of components and cost for assembling.

According to another aspect of the present invention, there is provided,an apparatus for heating a green tire by generating heat to a metalmember embedded in the green tire using electromagnetic induction,comprising: a heating coil for forming high frequency magnetic fieldalong a portion of an extending direction of said metal member; a highfrequency power supply for supplying high frequency power to saidheating coil, and a magnetic material member for inducing high frequencymagnetic field formed by said heating coil to said metal member.

With above construction, since high frequency magnetic field to beproduced by the heating coil passes through the metal member and isformed to converge onto the magnetic material, magnetic flux densitypassing through the metal member becomes large and the metal member canbe induction-heated efficiently.

According to another aspect of the present invention, there is provided,an apparatus for heating a green tire by generating heat to a metalmember embedded in the green tire using electromagnetic induction,comprising: a heating coil for forming high frequency magnetic fieldalong a portion of an extending direction of said metal member; a highfrequency power supply for supplying high frequency power to saidheating coil, and frequency changing means for changing the frequency ofpower to be supplied by said high frequency power supply.

The structure of the metal member embedded in the inside of tire isdifferent according to type or size of the tire. With aboveconstruction, since the frequency can be changed suitably in response towire diameter or current permeate depth thereof, it is possible to heatthe metal member by induction efficiently.

Here, the apparatus can further comprise a condenser for causing aresonance current to said heating coil.

With above construction, since the resonance current is formed by meansof the condenser, heat generation efficiency of the whole apparatus canbe improved, and it is possible to improve the power-factor and to heatthe metal member by induction efficiently.

Moreover, the apparatus can further comprises a voltage detector fordetecting voltage applied to both ends of said condenser, and saidfrequency changing means may control the frequency of power to besupplied by said high frequency power supply on the basis of voltagevalue detected by said voltage detector.

According to another aspect of the present invention, there is provided,an apparatus for heating a green tire by generating heat to a metalmember embedded in the green tire using electromagnetic induction,comprising: a heating coil for forming high frequency magnetic fieldalong a portion of an extending direction of said metal member; a highfrequency power supply for supplying high frequency power to saidheating coil, and relative distance adjusting means which is capable ofadjusting the distance between said heating coil and said metal member.

With above construction, since the magnetic flux density passing throughthe metal member can be adjusted in response to material constitution orshape of the metal member, it is possible to heat the metal member byinduction efficiently.

It is preferred that the apparatus for heating a green tire according tothe present invention is used as preheating apparatus for performing thepreheating before the green tire enters into a green tire vulcanizingapparatus.

With this invention, a large thickness portion which is difficult torise temperature is preliminarily temperature-raised to some degree, sothat it is effective to complete a later vulcanizing process in a moreshort time.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, other objects, features and advantages of the presentinvention will be better understood from the following description takenin conjunction with the accompanying drawings, in which:

FIG. 1 is a cross sectional view schematically showing a side of avulcanizing machine in a keeping process according to one embodiment ofthe invention;

FIG. 2 is a diagrammatic view showing a manufacturing process of a tireaccording to one embodiment of the invention;

FIG. 3 is a cross sectional view schematically showing a side of avulcanizing machine in a vulcanizing process according to one embodimentof the invention upon carrying in a green tire;

FIG. 4 is a cross sectional view schematically showing a side of avulcanizing machine in the keeping process according to one embodimentof the invention upon clamping a green tire mold;

FIG. 5 is a cross sectional view schematically showing a side of avulcanizing machine in the keeping process according to one embodimentof the invention upon completion of the clamping a green tire mold;

FIG. 6 is a cross sectional view schematically showing a tire mold and agreen tire during vulcanization; and

FIG. 7 is an exploded perspective view showing essential parts of thegreen tire;

FIG. 8 is an explanatory view showing a state of keeping the green tirewhile preheating it in the keeping process, (a) is a plan view, and (b)is a cross section view taken along the line X—X in (a);

FIG. 9 is an explanatory view showing a state of keeping the green tirewhile preheating it in the keeping process, (a) is a plan view, and (b)is a cross section view taken along the line X—X in (a);

FIG. 10 is an explanatory view showing a state of keeping the green tirewhile preheating it in the keeping process, (a) is a plan view, and (b)is a cross section view taken along the line X—X in (a);

FIG. 11 is an explanatory view showing a state of keeping the green tirewhile preheating it in the keeping process, (a) is a plan view, and (b)is a cross section view taken along the line X—X in (a);

FIG. 12 is an explanatory view showing a state of keeping the green tirewhile preheating it in the keeping process, (a) is a plan view, and (b)is a cross section view taken along the line X—X in (a);

FIG. 13 is an explanatory view showing a state of keeping the green tirewhile preheating it in the keeping process, (a) is a plan view, and (b)is a cross section view taken along the line X—X in (a);

FIG. 14 is an explanatory view showing a state of keeping the green tirewhile preheating it in the keeping process, (a) is a plan view, and (b)is a cross section view taken along the line X—X in (a);

FIG. 15 is a schematic view showing a green tire preheating apparatusaccording to one embodiment of the invention;

FIG. 16 shows a first coil means, which forms a high frequency magneticfield to a ring-belt-shaped metal member in a facial direction;

FIG. 17 shows a second coil means, which forms a high frequency magneticfield to a wire-ring-shaped metal member in a peripheral direction;

FIG. 18 shows the other shape example of a center core of the first coilmeans;

FIG. 19 shows another shape example of the center core of the first coilmeans;

FIG. 20 shows the other shape example of a side core of the first coilmeans;

FIG. 21 shows the other shape example of a coil of the first coil means;

FIG. 22 shows the other example of the first coil means;

FIG. 23 shows another example of the first coil means;

FIG. 24 shows another example of the first coil means;

FIG. 25 shows an example of the first coil means split in a widthdirection;

FIG. 26 shows an example of the first coil means split in a widthdirection;

FIG. 27 is a graph showing an example of heating a tread portion by thefirst coil means; and

FIG. 28 is a graph showing an example of heating a bead portion by thesecond coil means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the embodiment of the present invention will be explained withreference to FIGS. 1 to 28.

As shown in FIG. 2, a green tire preheating apparatus according to thepresent embodiment is provided in a keeping process. The keeping processis disposed between a forming process for forming a green tire 4 and avulcanizing process for vulcanizing the green tire 4, and temporarilykeeps the green tire 4 before vulcanizing process on the basis ofproduction plan. Also, operation of the green tire preheating apparatusand method of preheating the green tire by the apparatus in the keepingprocess will be explained later.

The vulcanizing process in which the green tire 4 is supplied from thekeeping process is provided with a vulcanizing machine for vulcanizingthe green tire 4. As shown in FIG. 3, the vulcanizing machine 1 has amold-fixing unit 2 set in a predetermined height position, andmold-lifting unit 3 which moves up and down with respective to themold-fixing unit 2. Also, as shown in FIG. 7, the green tire 4 has acarcass assembly 51 bent at both ends thereof, a metal bead wire 52provided in the bent portion of the carcass assembly 51, a rubber innerlinear 53 bonded to an inner peripheral surface of the carcass assembly51, a rubber tread member 54 and a side wall member 55 respectivelybonded to an outer peripheral surface and a side peripheral surface ofthe carcass assembly 51, and a metal belt member 56 provided between thetread member 54 and the carcass assembly 51, so that structure has themetal members(the bead wire 52, the belt member 56) inside the tire,that is in the tread portion 4 a and bead portions 4 c, 4 c′ havinglarge thickness.

As shown in FIG. 3, the mold-lifting unit 3 has an upper side mold 25 tobe contacted with an upper side wall 4 b′ of the green tire 4, a splitmold 26 positioned in the peripheral direction of the tread portion 4 aof the green tire 4, a first mold lifting means 27 for moving the upperside mold 25 and a slide segment 26 a of the split mold 26 up and down,an upper heating mechanism 28 for heating the upper side mold 25 to apredetermined temperature, a second mold lifting means 29 for moving theupper heating mechanism 28 and a stationary ring 26 b of the split mold26 up and down, and supporting member 30 for supporting these mechanisms27–29.

The upper heating mechanism 28 has a disc-shaped upper platen 32. Theupper platen 32 has an inner space to which high temperature vapor issupplied, and is generated a heat by vapor supplied to the inner spaceto heat the upper side mold 25 facially. Also, the upper heatingmechanism 28 has a platen support 33 for supporting the upper platen 32,and an insulating plate 34 interposed between the upper platen 32 andthe platen support 33 so as not to transfer heat of the upper platen 32to the platen support 33.

Also, a rod-shaped member 35 of the first mold lifting means 27 isinserted through the center portion of the upper heating mechanism 28 soas to be movable up and down. As shown in FIG. 4, a disc-shaped slideplate 36 is provided at a lower end of the rod-shaped member 35. In thelower surface of center portion of the slide plate 36, the upper sidemold 25 is fixed at a center side. An upper bead ring 40 formed so as toabut to the upper bead portion 4 c′ of the green tire 4 is provided atan inner periphery of the upper side mold 25. An annular thirdinduction-heating coil 41 is provided inside the upper bead ring 40.And, a high frequency power supply 24 of FIG. 6 is connected to thethird induction-heating coil 41, and the third induction-heating coil 41applies an intensive high frequency magnetic field to the upper beadportion 4 c′ of the green tire 4 by means of supply of high frequencypower, to firstly heat a bead wire 52 of the upper bead portion 4 c′ byinduction.

The slide segment 26 a having a plurality of segment molds 26 a′ formedof non-magnetic materials such as aluminum and the like is provided in alower surface of outer periphery of the slide plate 36. Each slidesegment 26 a is disposed on the same circumference about the upper sidemold 25 at equal intervals and is engaged to be movable centrally. In anouter direction of these slide segments 26 a, the stationary ring 26 bformed of non-magnetic materials is disposed. The stationary ling 26 bis fixed to a lower surface peripheral edge of the upper platen 32 andis adapted to move the slide segment 26 a forward and backward radiallywhile engaging to an outer surface of the slide segment 26 a. And, theslide segment 26 a forms a tubular mold corresponding to the treadportion 4 a of the green tire 4 when it has moved centrally by thestationary ring 26 b.

The mold-fixing unit 2 is disposed at the lower side of the mold-liftingunit 3. The mold-fixing unit 2 has a lower side mold 5 to be contactedwith an lower side wall 4 b of the green tire 4, a lower heatingmechanism 9 for heating the lower side mold 5 to a predeterminedtemperature, a center mechanism 10 provided at a center portion of thelower heating mechanism 9 and the lower side mold 5, and a base frame 11for supporting the center mechanism 10 and the lower heating mechanism9.

The lower heating mechanism 9 has a disc-shaped lower platen 6 forsupporting the lower side mold 6 facially. The lower platen 6 has aninner space to which high temperature vapor is supplied, and isgenerated a heat by vapor supplied to the inner space to heat the lowerside mold 5 facially. Also, the lower heating mechanism 9 has a platensupport 7 for supporting the lower platen 6, and an insulating plate 8interposed between the lower platen 6 and the platen support 7 so as notto transfer heat of the lower platen 6 to the platen support 7. And, inthe center portion of the lower heating mechanism 9 constructed as such,the center mechanism 10 is provided, and the center mechanism 10 isprovided with a holding mechanism 71 as a main part.

The holding mechanism 71 can be attached to and detached from themold-fixing unit 2 (the lower heating mechanism 9 and the lower sidemold 5), and as shown in FIGS. 1 and 3, has a bladder 20, a lower ringmechanism 12 holding a lower edge of the bladder 20, an upper ring 19holding an upper edge of the bladder 20, and a center post 22 passingthrough a center portion of the lower ring mechanism 12 and the upperring 19 and capable of coupling both rings 12, 19 to be fixed, with aconnection and positional relationships as described below.

Namely, as shown in FIG. 4, the lower ring mechanism 12 has a lower beadring 13 formed so as to be abutted to the lower bead portion 4 c of thegreen tire 4, a lower bladder ring 14 provided on a top surface of thelower bead ring 13 and supporting a lower edge of the bladder 20 bycooperating with the lower bead ring 13 therebetween, a clamp ring hub15 provided at an inner peripheral side of the lower bladder ring 14.Inside the clamp ring hub 15, distributing channels 15 a, 15 a forflowing a pressurized heating medium such as vapor, nitrogen gas, etc.are formed. And, these distributing channels 15 a, 15 a are communicatedfrom an upper end surface to a lower end surface of the clamp ring hub15, and the distributing channels 15 a, 15 a at the lower end areconnected to a pressurized heating medium supplying apparatus (notshown) via lines 17 a, 17 a and switching valves 17 b, 17 b.

Also, inside the lower bead ring 13, an annular first induction-heatingcoil 18 is provided. A high frequency power supply 24 of FIG. 6 forsupplying high frequency power is connected to the firstinduction-heating coil 18 to be disconnectable. And, the firstinduction-heating coil 18 applies an intensive high frequency magneticfield to the lower bead portion 4 c of the green tire 4 by means ofsupply of high frequency power, to firstly heat a bead wire 52 of thelower bead portion 4 c by induction.

In the center portion of the lower ring mechanism 12, the center post 22is erectly provided so as to be slidable vertically. An upper ring 19 isprovided at an upper end of the center post 22. The upper ring 19 has anupper bladder ring 21, and the upper bladder ring 21 supports an upperedge of the bladder 20. Meanwhile, a post lifting mechanism (not shown)for moving the center post 22 up and down to optional height position iscoupled to a lower end of the center post 22 to be disconnectable, andthe post lifting mechanism 22 constitutes the center mechanism 10together with the holding mechanism 71. And, the post lifting mechanismelevates the upper edge of the bladder 20 to raise the center post 22 upto upper limit position so that the bladder 20 is set to diametersmaller than that of hole of the green tire 4 when carrying out the tirehaving completed the vulcanization, while the post lifting mechanismlowers the center post 22 so that the bladder 20 is enlarged to adiameter capable of contacting to an inner wall surface of the greentire 4.

The bladder 20 to be contracted and enlarged by the center post 22presses the tire inner wall surface in a mold direction by supplying thepressurized medium when vulcanizing the green tire 4, and has a lowelongation material which is hard to deteriorate under high temperaturecondition as a constituent member. The low elongation material is formedto a shape similar to a shape of the tire inner wall surface havingfinished the vulcanization by vulcanizing the green tire 4. Namely, asshown in FIG. 6, the bladder 20 adopts the low elongation material whichis hard to deteriorate under high temperature condition, and has abladder body 20 a formed by shaping the material similar to shape of thetire inner wall surface of the tire having finished the vulcanization,and a plurality of magnetic member 20 b provided on the surface of thebladder body 20 a with equal intervals. The magnetic member 20 bcomprises metallic thin film having magnetism such as mesh metal,metallic deposition film, etc., and is formed such that a portioncorresponding to the tread portion 4 a of the green tire 4 becomeslarger area than the other portions.

The low elongation material is a material having properties ofelongation smaller than that of convention bladder rubber (for examplebutyl rubber) under high temperature condition at the vulcanizingtemperature and the particularly preferred material is that has anelongation in the range of 5%˜15% under high temperature condition of200° C. The reason why the elongation in the above range is preferred isthat if the elongation is less than 5%, the power for pressing uniformlythe whole green tire 4 is reduced so that the plasticity becomesinsufficient upon vulcanization, and if the elongation exceeds 15%, itis difficult to vulcanize the green tire 4 precisely as conventionalbladder rubber (for example butyl rubber).

As the low elongation material which is hard to deteriorate under hightemperature condition, knitted fabric or woven fabric using fabric suchas polyester, nylon, aramid, polyparaphenylenebenzobisoxazole (PBO), ormesh metal or high precise fabric, carbon-containing fabric, metalcoated fabric, resin coated fabric can be adopted, and material formedby mixing at least one type among above materials can be adopted. As aform of mixture, there is form of laminate structure formed bylaminating mesh metal on a polyester film or depositing metal film on apolyester film, or form woven while uniformly of locally distributingmetal coated fabric and high precise fabric. Also, in order to have airtightness, there is a form impregnated or coated with at least one offluorine, resin such as silicon, and elastomer into or onto a substratesuch as the above-mentioned knitted fabric or woven fabric. And, theseforms are suitably selected in accordance with design specification ofbladder (existence of heat generation by induction heating or intensity,etc.).

Inside the bladder 20, a second induction-heating coil 23 is disposed.The second induction-heating coil 23 is provided around the center post22, and is set to a coil height smaller than the distance in the casewhere the upper bladder ring 21 and the lower bladder ring 13 are mostapproached, and set to a coil diameter smaller than the outer diameterof both rings 21, 14 so as not to be contacted to the contracted bladder20. Also, the second induction-heating coil 23 is disposed so as not tobe contacted to both rings 21, 14 even in the case where the upperbladder ring 21 was lowered to a lower limit position. And, a highfrequency power supply 24 is connected to the second induction-heatingcoil 23 to be disconnectable, and the second induction-heating coil 23applies intensive high frequency magnetic field to the bladder 20 bysupply of high frequency power, thereby heating the magnetic member 20 bof the bladder 20 by induction firstly.

As shown in FIG. 2, the holding mechanism 71 is adapted to transportbetween vulcanizing process, keeping process and forming process by atransporting apparatus 43 in FIG. 1. And, the holding mechanism 71functions as a forming drum in the forming process, and functions toprevent deformation of the green tire 4 and to prevent displacement ofthe supporting center in keeping process or in transporting betweenprocesses, and functions as a main part of the above mentioned centermechanism 10 in vulcanizing process.

A tire-forming machine 61 of a single stage type is provided in theforming process. Also, the tire-forming machine 61 may be two-stagetype. As shown FIG. 2, the tire-forming machine 61 has a first drivingapparatus 62 and a second driving apparatus 63. The first drivingapparatus 61 and the second driving apparatus 62 are provided with afirst chuck mechanism 64 and a second chuck mechanism 65, respectively.These chuck mechanisms 64, 65 have chuck members 64 a, 65 a each capableof holding the center portions of the upper ring 19 and the lower ringmechanism 12 of the holding mechanism 71. And, both chuck mechanisms 64,65 are oppositely disposed such that the rotating shaft exist on thesame straight line, and are linked so as to rotate with same rotationalspeed and to stop at a same rotational angle. Moreover, the first chuckmechanism 64 on one side is adapted to forward and backward in arotating axis direction, and enlarges and contracts the ring distancebetween the upper ring 19 and the lower ring mechanism 12 of the holdingmechanism 71 when forming and taking out the green tire 4. Also, thetire forming mechanism 61 has a pressure gas supplying apparatus (notshown) for supplying pressure gas into the bladder 20 when taking outthe green tire 4, etc.

As shown in FIG. 2, the row tire 4 prepared in the forming process istransported in the state held to the holding mechanism 71, and conveyedto later keeping process or vulcanizing process. The keeping process hasa keeping depot 80. The keeping depot 80 has a plurality of keepingportion 81 keeping the green tire 4 while holding it with the holdingmechanism 71. Each keeping portion 81 is provided with a green tirepreheating apparatus as shown in FIG. 1. The green tire preheatingapparatus has a cylindrical loading table 82 formed to be contacted to alower surface of the lower ring mechanism 12, a preheatinginduction-heating coil 83 provided to surround the green tire 4 on theloading table 82, and a high frequency power supply 84 for supplyinghigh frequency power with respect to the preheating induction coil 83.And, the preheating coil 83 applies an intensive high frequency magneticfield to the tread portion 4 a of the green tire 4 by supplying highfrequency power from the high frequency power supply 84, thereby heatingthe belt member 56 of the tread portion 4 a by induction firstly.

In the above construction, a green tire preheating method will beexplained through the operation of the green tire preheating apparatus.

Firstly, as shown in FIG. 2, in the forming process, if the green tire 4which comprises a plural layers having the belt 56 and bead wire 52 inthe inside thereof by the tire forming machine 61, then the upper ring19 and the lower ring mechanism 12 of the holding mechanism 71 arecoupled to be fixed by the center post 22, and the first chuck mechanism64 is disengaged from the upper ring 19. And, after grasping the centerportion of the upper ring 19 by the transporting apparatus 43 of FIG. 1,the chuck mechanism 65 is disengaged from the lower ring 12, and theholding mechanism 71 is pulled out upwardly, thereby removing theholding mechanism 71 together with the green tire 4 from the tireforming machine 61. And, in the case where there exists a standby timeuntil vulcanizing the green tire 4, the green tire 4 is transported tothe green tire preheating apparatus in the keeping process while holdingthe green tire 4 with expanded state by the holding mechanism 71, andthe green tire 4 is kept while preheating it by the operation describedbelow.

Namely, as shown in FIG. 1, the holding mechanism 71 holding the greentire 4 is positioned above the loading table 82 in the green tirepreheating apparatus. And, the holding mechanism 71 is lowered to beloaded on the loading table 82, thereby keeping the green tire 4together with the holding mechanism 71. Thereafter, by supplying highfrequency power to the preheating coil 83 from the high frequency powersupply 84, the intensive high frequency magnetic field is applied to thetread portion 4 a of the green tire 4 to heat the belt member 56 of thetread portion 4 a by induction. Furthermore, high frequency magneticfield produced by the preheating coil 83 heats also the bead wire 52 ofthe bead portions 4 c, 4 c′ by induction. Thereby, even though the greentire 4 is kept under room temperature condition, since the tread portion4 a and the bead portions 4 c, 4 c′ of the green tire 4 having largethickness are heated from the inside of tire by the green tirepreheating apparatus, temperature of the green tire 4 is not lowered andis raised up to the temperature near the vulcanizing temperatureaccording to the degree of high frequency magnetic field application.

Next, in case of vulcanizing the green tire 4, the green tire 4 istransported to the vulcanizing process while holding it by the holdingmechanism 71, and the green tire is vulcanized by operations describedbelow. Namely, as shown in FIG. 3, by raising the mold-lifting unit 3firstly, the mold-lifting unit 3 is positioned above the mold-fixingunit 2. Thereafter, the green tire 4 together with the holding mechanism71 is transported between the mold-fixing unit 2 and the mold-liftingunit 3 by the transporting apparatus 43. As shown in FIG. 4, if theholding mechanism 71 is positioned above the center portion of themold-fixing unit 2, by lowering the holding mechanism 71, the holdingmechanism 71 is engaged to the mold-fixing unit. And, after releasingthe coupling-fixture between the upper ring 19 and the lower ringmechanism 12 by means of the center post 22, the center post 22 of theholding mechanism 71 is coupled to a post lifting mechanism (not shown),as well as the switching valves 17 a, 17 b and the induction-heatingcoils 18 23, 41 are connected to a gas supplying apparatus (not shown)and the high frequency power supply 24 of FIG. 6, respectively, therebylet them to function as the center mechanism 10.

Next, by advancing a cylinder rod 38 a from a second cylinder member 38of FIG. 3 and advancing a rod-shaped member 35 from a first cylindermember 37, the upper heating mechanism 28 and the slide plate 36 islowered to be disengaged each other and the slide segment 26 a is movedin an outer circumferential direction. Thereafter, as shown in FIG. 4with two dot-dashed line, by lowing the mold-lifting unit 3 whilemaintaining the upper heating mechanism 28 and the slide plate in adisengaged state, positioning the green tire 4 at the innercircumference side of the slide segment 26 a, and then moving slidesegment 26 a centrally by means of the stationary ring 26 b. And, asshown in FIG. 5, each slide segment 26 a is contacted each other to forma tubular mold corresponded to the tread portion 4 a of the green tire4, and the upper side mold 25 and the lower side mold 5 are contacted tothe upper portion and the lower portion of the mold, respectively,thereby completing the mold clamping.

High temperature vapor is supplied to the upper platen 32, the lowerplaten 6, and the stationary ring 26 b of the split mold 26, and byheating the upper and the lower side molds 25, 5 by means of bothplatens 6, 32 as well as by generating heat in the slide segment 26 a ofthe split mold 26, the green tire 4 surrounded with these molds 25, 5,26 a generate heat from outer surface sides thereof. Also, by supplyingthe pressure medium such as vapor, nitrogen gas under high temperatureand high pressure into the bladder 20 via a gas line 17 a, the greentire 4 is pressed to the inner wall surface of the mold by the bladder.And, by transferring the heat value of the pressure medium under hightemperature and high pressure to the green tire 4 via the bladder 20,the green tire 4 is heated from an inner surface side thereof.

Furthermore, as shown in FIG. 6, high frequency power is supplied toeach of induction-heating coils 18, 23, 41, 39 from the high frequencypower supply 24. The first induction-heating coil 18 and the thirdinduction-heating coil 41 supplied with high frequency power applyintensive high frequency magnetic field to the lower bead portion 4 cand the upper bead portion 4 c′ of the green tire 4, respectively,thereby heating the bead wires 52, 52 provided within the both beadportions 4 c, 4 c′ by induction firstly. Also, since the split mold 26is formed with non-magnetic material, a fourth induction-heating coil 39applies intensive high frequency magnetic field to the tread portion 4 aof the green tire 4, thereby heating the belt member 56 provided withinthe tread portion 4 a by induction firstly. Thereby, in the green tire4, in addition to the heating from the outer surface side and innersurface side thereof, since heating from the inside of tire is performedin the bead portions 4 c, 4 c′ and tread portion 4 a having largethickness, temperature of the whole tire is risen up to vulcanizingtemperature in a short time.

Moreover, in the green tire 4 transported from the keeping process,since the bead portions 4 c, 4 c′ and tread portion 4 a having largethickness is preheated near the vulcanizing temperature, the whole greentire 4 is risen up to vulcanizing temperature in a very short time afterinitiating the heating for vulcanization, even in the case where thetire is kept under room temperature condition for a long time.

Also, a process of keeping the temperature of the green tire 4 heated byinduction may be provided during the time until the vulcanizing isinitiated. Specifically, the green tire 4 preheated is received in atemperature keeping box, and then the heating is continued so as tomaintaining the green tire 4 near the preheating temperature just beforereaching to the vulcanizing process. Thereby, the green tire 4 havingcompleted the preheating up to predetermined temperature is preventedfrom temperature lowering due to radiation of heat, and heat uniformityof the green tire 4 can be improved.

The second induction-heating coil 23 supplied with high frequency powerapplies intensive high frequency magnetic field to the magnetic member20 b of the bladder 20, thereby generating heat from the bladder 20itself. Accordingly, upon transferring the heat value of the powermedium to the green tire 4 via the bladder 20, since the delay of theheat transfer time due to the bladder 20 is suppressed minimally, thetemperature of the green tire 4 is raised up to the vulcanizingtemperature in a more short time. And, vulcanization of the green tire 4is performed while the green tire 4 is maintained in a vulcanizingtemperature.

During the vulcanization of the green tire 4, the bladder 20 presses thegreen tire 4 in a mold direction to form the green tire. At this time,since the bladder 20 is formed of a low elongation material having shapesimilar to that of the inner wall surface of the green tire havingcompleted the vulcanization, the shape of the inner wall surface of thegreen tire having completed the vulcanization surely appeared even inthe case where pressure of the pressure medium has somewhat changed.Accordingly, if the bladder 20 presses the green tire 4 to perform theforming process, a tire having completed the vulcanization which isformed in a high precision is obtained.

As such, when a vulcanized tire is obtained, as shown in FIG. 4, afterhaving opened the mold by the operation opposite to the operationdescribed above, the center post 22 is raised to contract the bladder20. And, the vulcanized tire 4′ is removed from the holding mechanism 71to be taken to the outside, and the holding mechanism 71 is taken to theoutside, and then the vulcanized tire 4′ is transported to the laterprocess as well as the holding mechanism 71 is transported to theforming process. Thereafter, by means of above operation, a new greentire 4 is carried in, to repeat the vulcanizing, but in the case ofrepeating the such vulcanizing, since the low elongation material of thebladder 20 is hard to deteriorate under high temperature condition, thelow elongation material maintains its original property. Accordingly,even in the stage that the vulcanization has repeated large number oftimes, since the bladder 20 makes shape of the inner wall surface of thevulcanized tire to be surely appeared, it is possible to use the bladder20 for a ling time.

As described above, in this embodiment, before vulcanizing the greentire 4 having metal members embedded therein, as shown in FIG. 1, thepreheating method of the green tire by induction-heating the metalmember is performed, so that the inside of the green tire of which thetemperature raising is mostly delayed in vulcanization is preheat whileit is heated in prior, thereby it is possible to complete thevulcanization in a short time. Specifically, at least one of the beltmember 56 (metal member) and the bead wire 52 (metal member) embedded inthe inside of tire, that is, the tread portion 4 a and/or bead portion 4c, 4 c′ is heated by induction, so that particularly the inside of tire,that is the tread portion 4 a and bead portions 4 c, 4 c′ having largethickness is preheated, thereby the vulcanization can be completed moresurely in a short time. Also, in this embodiment, although the case thatthe metal member is embedded in the tread portion 4 a and bead portions4 c, 4 c′ was explained, the present invention is not limited to thiscase, and can be applied to the case that the metal member is embeddedin an optional portion having large thickness. For example, in case thatthe metal members are embedded in the sidewalls 4 b, 4 b′ which becomethe sidewall portion, at least one of the metal member embedded in thetread portion 4 a, the bead portions 4 c, 4 c′ and the sidewalls 4 b, 4b′ may be induction-heated.

In this embodiment, the green tire preheating method is practiced by agreen tire preheating apparatus which has a loading table 82 (tiresupporting means) for detachably supporting the green tire 4 in apredetermined posture, and a preheating coil 83 for applying highfrequency magnetic field with respect to the green tire 4 supported onthe loading table 82 (tire supporting means) to induction-heat the metalmember of the green tire 4 by high frequency magnetic field.

The green tire preheating apparatus in this embodiment is constitutedsuch that the metal members of the tread portion 4 a and bead portions 4c, 4 c′ are induction-heated by the preheating coil 83 disposed aroundthe green tire 4, to be preheated while holding the green tire 4 fromthe inside thereof by the holding mechanism 71, but the presentinvention is not limited to this embodiment and may be constituted suchthat only the green tire 4 is kept and preheated so as to be applicableto a bladder type or a bladder-less type of a vulcanizing machine.

Accordingly, the green tire preheating apparatus may have a constitutionshown in FIGS. 8 to 16. The constitution of FIGS. 8( a) and (b) will beexplained in detail. The green tire preheating apparatus has a loadingtable 90 for loading the green tire 4, and a tread portion-preheatingcoil 91 disposed along the tread portion 4 a of the green tire 4 on theloading table 90 for generating a high frequency magnetic field. Arotational driving apparatus (not shown) is coupled to the centerportion of the lower surface of the loading table 90 via a rotatingshaft 95, and the rotational driving apparatus rotates the green tire 4together with the loading table 90 horizontally when keeping the greentire 4. Inside the loading table 90, a lower bead portion-preheatingcoil 92 is provided, and the lower bead portion-preheating coil 92 isdisposed along the lower bead portion 4 c for applying an intensive highfrequency magnetic field to the bead wire 52 (metal member) of the lowerbead portion 4 c.

Also, in the center portion of the upper surface of the loading table90, a supporting member 93 is vertically provided. The supporting member93 supports an upper bead portion-preheating coil 94, and the upper beadportion-preheating coil 94 is set to a coil diameter smaller than thatof the hole of the green tire 4. And, the upper bead portion-preheatingcoil 94 is disposed along the upper bead portion 4 c′ at anapproximately same height position as the upper bead portion 4 c′ forapplying an intensive high frequency magnetic field to the bead wire 52(metal member) of the upper bead portion 4 c′.

In the above constitution, when keeping the green tire 4, the green tireis moved horizontally by a transporting apparatus (not shown) to bepositioned above the loading table 90, and then is lowered vertically toinsert the upper bead portion-preheating coil 94 through the tire holeand is loaded on the loading table 90. Thereafter, the loading table0.90 and the green tire 4 rotates horizontally by the rotational drivingapparatus (not shown) via the rotating shaft 95, as well as each of thepreheating coils 91, 92, 94 is supplied with high frequency power fromthe high frequency power supply (not shown).

The tread portion-preheating coil 91 supplied with high frequency powerapplies high frequency magnetic field to the tread portion 4 a with highmagnetic flux density, to induction-heat the belt member 56 of the treadportion 4 a efficiently. Meanwhile, respective bead portion-preheatingcoils 92, 94 apply high frequency magnetic field to the respective beadportions 4 c, 4 c′ with high magnetic flux density, to induction-heatthe bead wire 52 of the respective bead portions 4 c, 4 c′ efficiently.By means of this, the inside of tire, particularly the tread portion 4 aand bead portions 4 c, 4 c′ having large thickness of which thetemperature rising is delayed upon vulcanization, can be preheatedsufficiently.

Since the green tire 4 has rotated horizontally, the treadportion-preheating coil 91 and the upper bead portion-preheating coil 94become a state that has moved relatively along the green tire 4.Accordingly, even in the case that the preheating coils 91, 94 applyhigh frequency magnetic field non-uniformly to the thread portion 4 aand the upper bead portion 4 c′, 4 c′ of the green tire 4 due to lowassembling precision or low processing precision, high frequencymagnetic field can be uniformly applied through the whole green tire 4to induction-heat it. Thereby, it is not necessary to assemble orprocess the preheating coils 91, 94 with high precision, and operationsfor assembling and processing can be facilitated.

Also, the constitution of FIGS. 9( a) and (b) will be explained indetail. The green tire preheating apparatus has a loading table 96 forloading the green tire 4. The loading table 96 is supported and fixed ona supporting table 97. And, through hole 96 a is formed in the centerportion of the loading table 96, and a rotational supporting shaft 98 isrotatably inserted through the through hole 96 a. In the upper portionof the rotational supporting shaft 98 above the loading table 96, acolumnar preheating coil 99 is fixed. The columnar preheating coil 99 isset to a coil diameter smaller than the tire hole of the tire 4 so as tobe inserted through the hole of the tire 4. Moreover, the columnarpreheating coil 99 is formed and disposed such that both ends thereofare positioned at the both bead portions 4 c′, 4 c, in order to applyintensive high frequency magnetic field to the bead wire 52 (metalmember) of the respective bead portions 4 c, 4 c′ and the belt member 56(metal member) of the tread portion 4 a. Meanwhile, a rotational drivingapparatus (now shown) is coupled to the lower end of the rotationalsupporting shaft 98, and the rotational driving apparatus rotates therotational supporting shaft 98 to swing the columnar preheating coil 99within the green tire 4.

In the case of keeping the green tire 4, the green tire is movedhorizontally by a transporting apparatus (now shown) to be positionedabove the loading table 96, and then is lowered vertically to insert thecolumnar preheating coil 99 through the tire hole and is loaded on theloading table 96. Thereafter, the columnar preheating coil 99 is swungby the rotational driving apparatus (not shown) via the rotationalsupporting shaft 98 within the green tire, as well as the columnarpreheating coil 99 is supplied with high frequency power from the highfrequency power supply (not shown).

The columnar preheating coil 99 supplied with high frequency powerapplies high frequency magnetic field to the tread portion 4 a and beadportions 4 c, 4 c′ with high magnetic flux density, to induction-heatthe bead wire 52 of respective bead portions 4 c, 4 c′ as well as beltmember 56 of the tread portion 4 a efficiently. By means of this, theinside of tire, particularly the tread portion 4 a and bead portions 4c, 4 c′ having large thickness of which the temperature rising isdelayed upon vulcanization can be preheated sufficiently.

Since the columnar preheating coil 99 is swung about the rotationalsupporting shaft 98, the columnar preheating coil 99 becomes a statethat has moved relatively along the green tire 4. Accordingly, even inthe case that the columnar preheating coil 99 applies high frequencymagnetic field non-uniformly to the thread portion 4 a and the beadportions 4 c, 4 c′ of the green tire 4 due to low assembling precisionor low processing precision, high frequency magnetic field can beuniformly applied through the whole green tire 4 to induction-heat it.Thereby, it is not necessary to assemble or process the columnarpreheating coil 99 with high precision, and operations for assemblingand processing can be facilitated.

The constitution of FIGS. 10( a) and (b) will be explained in detail.The green tire preheating apparatus has a loading table 90 for loadingthe green tire 4. A rotational driving apparatus and a liftingapparatus, which are not shown are coupled to the center portion of thelower surface of the loading table 90 via a rotating shaft 95, and therotational driving apparatus rotates the green tire 4 together with theloading table 90 horizontally when keeping the green tire 4. Also, thelifting apparatus raises the loading table 90 up to the keeping positionshown by solid line when keeping the green tire, and lowers the greentire 4 to the carrying in and out position shown by two dot-dash whencarrying in and out the green tire 4.

Inside the loading table 90, a lower bead portion-preheating coil 92 isprovided, and the lower bead portion-preheating coil 92 is disposedalong the lower bead portion 4 c for applying an intensive highfrequency magnetic field to the bead wire 52 (metal member) of the lowerbead portion 4 c. Meanwhile, above the loading table 90, an upper beadportion-preheating coil 100 is disposed. The upper beadportion-preheating coil 100 is set to a coil diameter approximatelycorresponded to the tire diameter of the green tire 4. And, the upperbead portion-preheating coil 100 is disposed along the upper beadportion 4 c′ above and in the vicinity of the upper bead portion 4 c′for applying an intensive high frequency magnetic field to the bead wire52 (metal member) of the upper bead portion 4 c′.

Furthermore, the green tire preheating apparatus has a local preheatingcoil 101 formed with inverse U shape. When the green tire 4 is loaded onthe loading table 90 and is raised up to the keeping position (shown bysolid line), the local preheating coil 101 is disposed to be matchedwith a part of the tread portion 4 a of the green tire 4. And, the localpreheating coil 101 is connected to a high frequency power supply 102,and applies high frequency magnetic field to the tread portion 4 a bythe power supply from the high frequency power supply 102.

In the case of keeping the green tire 4, the loading table 90 is loweredto the carrying in and out position, and then the green tire 4 is movedby a transporting apparatus (not shown) to be positioned between theloading table 90 and the upper bead portion-preheating coil 100. And,the green tire 4 is lowered vertically to be loaded on the loading table90. Thereafter, by raising the loading table 90 up to the keepingposition shown by solid line, the green tire 4 on the loading table 90approaches to the local preheating coil 101 and the upper beadportion-preheating coil 100.

In this manner, if the green tire 4 is set to the keeping position, thegreen tire 4 is rotated horizontally by the rotational driving apparatus(not shown) via the loading table 90, and each of the preheating coils92, 100, 101 is supplied with high frequency power from the highfrequency power supply 102. The lower bead portion-preheating coil 92and the upper bead portion-preheating coil 100 supplied with highfrequency power apply high frequency magnetic field to the whole beadportions 4 c, 4 c′ with high magnetic flux density, to induction-heatthe whole bead wire 52 of the bead portions 4 c, 4 c′ efficiently.

Also, the local preheating coil 101 efficiently induction-heats a partof the belt member 56 of the tread portion 4 a, that is, a part mostlyapproached to the coil 101. At this time, since the green tire 4 hasrotated horizontally, the local preheating coil 101 becomes a state ofmoving relatively along the tread portion 4 a of the green tire 4.Accordingly, even in the case that the local preheating coil 101 hasheated a part of the tread portion 4 a, it becomes the state equivalentto the case that high frequency magnetic field for induction-heat isapplied uniformly over the whole thread portion 4 a by the rotation ofthe green tire 4. As a result of this, in comparison with the case thatthe preheating coil is formed so as to surround the whole tread portion4 a, the local preheating coil 101 can be formed in a small size,thereby it is possible to make the green tire preheating apparatus becompact and low power consumption.

Furthermore, since the green tire 4 is rotated, the upper beadportion-preheating coil 100 becomes a state of moving relatively alongthe green tire 4. Accordingly, even in the case that the upper beadportion-preheating coil 100 apply high frequency magnetic fieldnon-uniformly to the upper bead portion 4 c′ of the green tire 4 due tolow assembling precision or low processing precision, high frequencymagnetic field for induction-heat can be uniformly applied over thewhole green tire 4. Thereby, it is not necessary to assemble or processthe upper bead portion-preheating coil 100 with high precision, andoperations for assembling and processing can be facilitated.

In the green tire preheating apparatus of FIGS. 8 and 10, a movingmechanism for rotating one of the green tire 4 and the preheat coil(upper bead portion-preheating coil 94, etc.) is constituted by therotational driving apparatus (not shown) or the rotating shaft 95, etc.,but the present invention is not limited to these embodiments. Namely,the moving mechanism may be a constitution that has moving means forperforming at least one of rotational moving of the loading table 90 andswivel moving of the preheating coil, so as to relatively moving thepreheating coil along the green tire 4 on the loading table 90 (tiresupporting means) in the circumferential direction of the green tire 4.

As shown in FIG. 11, a local preheating coil 111 can be disposed insidethe green tire 4. The difference from the FIG. 10 is that the localpreheating coil 111 for the tread of the green tire 4 is disposed insidethe green tire 4 so as to be corresponded to a part of the tread portion4 a. The other features are similar to those of FIG. 10, so that samereference numerals are given and detail descriptions thereof areomitted. When the loading table 90 having the green tire 4 loadedthereon is raised up to a keeping position (shown by solid line), thelocal preheating coil 111 is moved toward the outside and is disposedinside the green tire 4 so as to be corresponded to a part of the treadportion 4 of the green tire 4.

As shown in FIG. 10, when the local preheating coil 101 is disposedoutside the green tire 4, there has been a case that a distance betweenthe coil 101 and the metal belt member 56 becomes more distant dependingon type of the tire. However, an inner liner portion at the innersurface side of the green tire 4 has sufficiently thin structure andthickness change thereof is small, contrary to the tread layer havinglarge thickness at the outside of the green tire. Accordingly, as shownin FIG. 11, by disposing the local preheating coil 111 inside the greentire 4 so as to be corresponded to a part of the tread portion 4 a ofthe green tire, a distance between the coil 111 and the metal beltmember 56 becomes near, and it becomes possible to apply a sufficientalternating magnetic field to the belt member (metal member) 56.

Also, in order to induce high frequency magnetic field to be formed bythe local preheating coil 111 to the metal belt member 56, it ispossible to dispose the magnetic material 112, 112 so as to becorresponded to a part of the tread portion 4 a of the green tire. Sincethe alternating magnetic field generated around the local preheatingcoil 111 passes through the metal belt member 56 within the green tire 4by way of the magnetic materials 112, 112, magnetic flux density passingthrough the metal belt member 56 becomes large and a circumferentialpart of the belt member 56 of the tread portion 4 a is induction-heatedefficiently. At this time, since the green tire 4 is rotated, the localpreheating coil 111 and the magnetic material 112 become a state ofmoving relatively along the tread portion 4 a of the green tire 4.Accordingly, even in the case that the local preheating coil 111 hasheated a part of the tread portion 4 a, it becomes the state equivalentto the case that high frequency magnetic field for induction-heat isapplied uniformly over the whole thread portion 4 a by the rotation ofthe green tire 4.

As shown in FIG. 12, it is possible the change the relative positionalrelationship between the local preheating coil, etc. and the green tire.The difference from the FIG. 10 is that a local preheating coil 121, alower bead portion-preheating coil 122, and an upper beadportion-preheating coil 123 are connected to hydraulic servo actuators125, 126, 127, respectively, which are relative distance adjustingmeans. The other features are similar to those of FIG. 10, so that samereference numerals are given and detail descriptions thereof areomitted. By operating the hydraulic servo actuators 125, 126, 127, it ispossible to move the local preheating coil 121 in radial direction ofthe green tire 4 and to move the lower bead portion-preheating coil 122and the upper bead portion-preheating coil 123 vertically, respectively.

Here, the magnetic flux densities of the alternating magnetic field tobe generated at the periphery of the induction-heating coil are varydepending on the distance from the induction-heating coil. Accordingly,by moving each preheating coil to adjust the distance from the greentire, the magnetic flux density passing through each metal member can beproperly adjusted depending on the material constitution and shape, sothat it is possible to heat the green tire efficiently.

Although the hydraulic servo actuators 125, 126, 127 are used asrelative distance adjusting means in FIG. 12, the design may suitably bechanged for example, by using the mechanism combining a motor with arack and pinion. Moreover, in this embodiment, the coils 121, 122, 123move with respect to the green tire 4, but to the contrary, the greentire 4 may move with respect to the coils 121, 122, 123 by providing thegreen tire 4 with relative distance adjusting means.

As shown in FIG. 13, it is possible to change the frequency in the localpreheating coil and the like. The difference from the FIG. 10 is thathigh frequency power supply circuit having frequency changing means forthe local preheating coil 101 is shown. The other features are similarto those of FIG. 10, so that same reference numerals are given anddetail descriptions thereof are omitted. The high frequency power supplycircuit 131 is constituted, by having an AC power supply 132, arectifying circuit 133, an inverter 134, a driver 135, a voltagedetector 136, and resonance condenser 137.

The AC power supply 132 is converted into DC by the rectifying circuit133 and converted into AC power supply having predetermined frequency byON and OFF of the switching element of the inverter 134. ON and OFF ofthe switching element of the inverter 134 is controlled by the driver135. Namely, the driver 135 can change the frequency over a wide range.By the driver 135 which is a frequency changing means, the AC powersupply frequency can be changed preferably in a 50 Hz˜100 KHz, morepreferably in a 10˜30 KHz. Since the constitution of the metal beltmember 56 becomes different depending on the size and type of the greentire, by changing into and setting suitable frequency according to itswire diameter, current infiltration depth, it is possible to improve theheat generation efficiency and to suppress the variation of the heatgeneration of the belt member 56.

Since the belt member 56 exists inside the insulating material and isformed of fine metal wire or metal plate, cross sectional area to whichmagnetic field emitted from the local preheating coil 101 is directed issmall, and induction over-current is hard to flow. Namely, thepower-factor of the high frequency power supply circuit 131 becomes low.Therefore, it is desirable to connect the condenser 137 for generatingthe resonance current to the local preheating coil 101 in parallel or inseries. For example, if switching frequency of the inverter 134 is f0,electrostatic capacity of the condenser 137 is determined such thatresonance frequency of the condenser 137 becomes f1=f0×n (integer morethan 2). Then, current i1 flowing through the coil 101 becomes more thantwo times with respect to current i0 at the inverter 134, and currentamount of wiring to the inverter 134 and the condenser 137 becomes smallto suppress heat generation, thereby power-factor of the whole highfrequency power supply circuit 131 is improved.

The method of determining uniquely the resonance frequency f1 of thecondenser 137 from the frequency f0 of the inverter 134 was explained,but the method of providing the voltage detector 136 for detecting thevoltage of the condenser 137, and corresponding to optional frequency ofthe inverter 134 may be employed. The voltage detector 136 measuresvoltage at both ends of the condenser 137 in a real time, and ON and OFFtiming of the switching element of the inverter 134 is performed by thefeedback value of said voltage value. Specifically, control to makeswitch of the inverter ON near the time of completing one cycle ofresonance between condenser 137 and coil 101 is performed.

Now, high frequency power supply circuit provided with the frequencychanging means to the local preheating coil 101 for the tread is shown,but same effect is attained by forming the high frequency power supplycircuit provided with the frequency changing means to the localpreheating coil 101 for the bead portion.

Also, forms of preferable induction heating will be described withreference to FIG. 14. The constitution of FIGS. 14( a) and (b) will beexplained in detail. The green tire preheating apparatus has a loadingtable 140 for loading the green tire 4, a tread portion-preheating coil144 disposed to be corresponded to the tread portion 4 a of the greentire 4 on the loading table 140 for generating high frequency magneticfield, and bead portion-preheating coils 146, 147 disposed to becorresponded to the bead portions 4 c, 4 c′ of the green tire 4 forgenerating high frequency magnetic field. In the center portion of thelower surface of the loading table 140, a rotational driving apparatus(not shown) is coupled via a rotating shaft 141, and the rotationaldriving apparatus rotates horizontally the green tire together with theloading table 140 when keeping the green tire 4. Also, a supportingmember 142 is disposed above the loading table 140, and a liftingapparatus (not shown) is coupled to a center portion of the uppersurface of the supporting member 142 via a supporting shaft 143.

The tread portion-preheating coil 144 is disposed outside the green tireso as to be corresponded to a part of the tread portion 4 a of the greentire 4. The tread portion-preheating coil 144 is a coil wound in spiralshape, and has a core (magnetic material) disposed therein. Also, thetread portion-preheating coil 144 has a shape to be corresponded toshape of the tread portion 4 a. Here, the tread portion-preheating coil144 is disposed such that the magnetic field direction of high frequencymagnetic field to be formed around the tread portion-preheating coil 144coincides with a direction following a part of the circumferentialdirection of the metal belt member 56 of the tread portion 4 a.

The lower bead portion-preheating coil 146 is disposed along the lowerbead portion 4 c below and in the vicinity of the lower bead portion 4 cfor applying an intensive high frequency magnetic field to the bead wire52 (metal member) of the lower bead portion 4 c. The lower beadportion-preheating coil 146 is a coil which is wound in a spiral shapefacially, and the spiral coil is constituted by the electric wirewinding bundled with a coil so as to surround around the center throughportion. Here, the lower bead portion-preheating coil 146 in which theelectric wire winding is more than 60 mm and width of the center throughportion is about the same as that of the electric wire winding.

On the other hand, the upper bead portion-preheating coil 47 is disposedalong the upper bead portion 4 c′ above and in the vicinity of the upperbead portion 4 c′ for applying an intensive high frequency magneticfield to the bead wire 52 (metal member) of the upper bead portion 4 c′.As the upper bead portion-preheating coil 147, one that has same shapeas the lower bead portion-preheating coil 146 is used.

Each one of temperature sensor 148 is disposed at the inner surface andouter surface of the tread portion of the green tire 4, respectively. Bydetecting the temperature of the inner surface and the outer surface ofthe green tire 4 using the temperature sensor 148, it is possible topractice the control for maintaining at a desirable temperature byestimating the temperature of the metal belt member 56 of the treadportion 4 a. Here, the quantity and the disposing position of thetemperature sensor to be disposed for detecting the outer surfacetemperature of the green tire 4 may be suitably changed. Moreover, anyof the contact type or non-contact type of temperature sensor may beused. Also, the temperature sensor can be used not only for the controlbut also for the error detection. For example, by detecting thetemperature rising (ΔT° C.) after 2˜3 minutes from preheatinginitiation, weather the preheating state is good or not is decided.

Also, a guide roller 149 is mounted so as to contact with outer surfaceof the green tire 4. When the green tire 4 together with the loadingtable 140 and the rotational supporting member 142 rotates horizontallyupon keeping, the green tire 4 is rotated while outer surface thereof isguided in the guide roller 149. Also, it is possible to dispose theguide roller 149 so as to contact with inner surface of the green tire.

The tread portion-preheating coil 144 is disposed between the green tire4 and the green tire 4′ mounted opposite to the green tire 4, and isdisposed along a part of respective tread portions 4 a, 4 a′ of thegreen tire 4 and the green tire 4′.

In the above constitution, when keeping the green tire 4, the green tireis moved horizontally by a transporting apparatus (not shown) to bepositioned above the loading table 140, and then is loaded on theloading table 140 by vertically lowering the supporting member 142.Thereafter, the loading table 140 and the green tire 4 rotatehorizontally by the rotational driving apparatus (not shown) via therotating shaft 141, as well as each of the preheating coils 144, 146,147 is supplied with high frequency power from the high frequency powersupply (not shown).

The tread portion-preheating coil 144 supplied with high frequency powerapplies high frequency magnetic field to the tread portion 4 a with highmagnetic flux density, to induction-heat the belt member 56 of the treadportion 4 a efficiently. Particularly, in the case where high frequencymagnetic field is formed in a circumferential direction of the metalbelt member 56 of the tread portion 4 a, since high frequency magneticfield is formed along the metal belt member 56, magnetic flux densitypassing through the metal belt member 56, 56 becomes large and acircumferential part of the belt member 56 of the tread portion 4 a canbe induction-heated efficiently.

Meanwhile, respective bead portion-preheating coils 146, 147 apply highfrequency magnetic field to the respective bead portions 4 c, 4 c′ withhigh magnetic flux density, to induction-heat the bead wire 52 of therespective bead portions 4 c, 4 c′ efficiently. Particularly, in thecase where spiral bead portion-preheating coils 146, 147 are used, highfrequency magnetic field is formed along the circumferential directionof the bead wire 52 (metal member) of the lower bead portion 4 c and theupper bead portion 4 c′. Accordingly, even in the case that the outersurface of the green tire and coil are apart from each other, it ispossible to apply sufficient alternating magnetic field particularly tothe bead wire 52 of the bead portions 4 c, 4 c′ having large thicknessof which the temperature rising is delayed upon vulcanization.

Since the green tire 4 has rotated horizontally, the treadportion-preheating coil 144, the lower bead portion-preheating coil 146and the upper bead portion-preheating coil 147 become a state of movingrelatively along the green tire 4. Accordingly, even in the case thatthe preheating coils 144, 146, 147 apply high frequency magnetic fieldnon-uniformly to the thread portion 4 a, the lower bead portion 4 c andthe upper bead portions 4 c′ of the green tire 4 due to low assemblingprecision or low processing precision, high frequency magnetic field forinduction-heat can be uniformly applied through the whole green tire 4.Thereby, it is not necessary to assemble or process the preheating coils144, 146, 147 with high precision, and operations for assembling andprocessing can be facilitated.

Additionally, since by providing the guide roller for guiding the outersurface of the green tire 4, relative distance between the metal beltmember 56 of the tread portion 4 a and the tread portion-preheating coil144 is kept constant and magnetic flux density of the magnetic fieldpassing through the belt member 56 can be maintained constant, so thattemperature irregularity of the heating portion can be reduced.

Also, thread portion-preheating coil 144 is disposed between the greentire 4 and green tire 4′ and rotates respectively, so that the metalbelt member 56 of tread portions 4 a, 4 a′ of the green tire 4 and greentire 4 a′ can be induction-heated at the same time. Also, by connectinga plurality of coils to one high frequency power supply, the pluralityof the green tire preheating apparatus can be controlled with integratedform. By having above constitution, since it is unnecessary to mountindividually the high frequency power supply and the coil with respectto each green tire preheating apparatus, cost of green tire preheatingapparatus can be saved.

In the above embodiment, the heating apparatus of the present inventionis explained mainly regarding to a preheating apparatus, but may beapplied to the vulcanizing apparatus by changing its shape suitably.

A green tire preheating apparatus and method according to anotherembodiment of the present invention will be explained with reference toFIG. 15. FIG. 15( a) is a top view of main part of the green tirepreheating apparatus 201, and FIG. 15( b) is a side cross sectional viewof main part of the green tire preheating apparatus 201.

The constitution of an apparatus shown in FIG. 15 will be explained. Agreen tire preheating apparatus 201 comprises a holding mechanism 211for rotatably holding a green tire 204, a local preheating coil 212 fora tread portion(first coil means), a local preheating coil 213 for apair of bead portion (second coil means), a pressing means 214 forpressing the inside of the green tire 214 to be held by the holdingmechanism 211.

In FIG. 15, the holding mechanism 211 has an upper supporting plate 221for an upper bead portion 204 c of the green tire 204, a lowersupporting plate 222 for a lower bead portion 204 c of the green tire204, a supporting shaft 223 for the upper supporting plate 221, and arotating shaft 224 for the lower supporting plate 222. A liftingapparatus (not shown) is coupled to the supporting shaft 223, and theupper supporting plate 221 is adapted to freely move up and down whenattaching and detaching the green tire 204. A rotational drivingapparatus (not shown) is coupled to the rotating shaft 224, and therotating shaft can rotate the green tire 204 horizontally. The pressingmeans 214 consists of a central passage 225 of the rotating shaft 224,and a pressure fluid supplying source 226 to the passage 225. When thepressure fluid is supplied inside the green tire 204 tightly held at apart of the bead portion 204 c through the passage 225, the green tire204 expands to a predetermined shape and does not cause a deformation.

The local preheating coil 212 for the thread portion 204 a (first coilmeans) is disposed outside the green tire 204 along a part of the treadportion 204 a of the green tire 204. As shown in FIG. 16, the localpreheating coil 212 has a coil 231, center core 232, and side cores 233,233. The coil 231 is wound around the planar center core 232, and bothends thereof become a hollow core-shaped enlarged portion or a deformedportion 231 a to swell toward a sidewall portion 204 b. The side cores233, 233 have a width larger than the thickness of the center core 232,and are formed with a protruded portion or a deformed portion 233 a, 233a, which is protruded toward the shoulder portion 204. The highfrequency magnetic field from the coil 231 is formed in a roof shape ina circumferential direction via the center core 232 and side cores 233,233. A steel belt 205 is present in a circumferential direction of thegreen tire 204 and high frequency magnetic field is formed along thesteel belt 205, so that the magnetic field is concentrated on the steelbelt 205 to perform electromagnetic induction heating efficiently.

Both ends in a width direction of the steel belt 205 is positioned up tocenter of the shoulder portion at an end of the side wall portion 204 b,and if the heat generation density of the steel belt 205 is uniform, theheating of the shoulder portion at the end of the side wall portion 204b tends to be delayed compared to the center portion of the treadportion 204 a. Also, steel belt 205 itself is curved in a widthdirection, and distance between the ends in a width direction of thecoil 231 and the steel belt 205 becomes distant at the shoulder portionat the end of the side wall portion 204 b compared to the center portionof the tread portion 204 a. Therefore, it is necessary to increase themagnetic flux density at both ends in a width direction of the steelbelt 205 and promote the heating of the shoulder portion at the end ofthe side wall portion 204 b, then the upper and the lower of the coil231 become an enlarged portion or a deformed portion, and high frequencymagnetic field is curved toward the side wall portion 204 b. Also, dueto the projected portion or the deformed portion 233 a, 233 a of theside cores 233, 233, the shoulder portion at the end of the sidewallportion 204 b has a magnetic flux denser than that at the center portionof the tread portion 204 a. As such, by means of the enlarged portion orthe deformed portion 231 a of the coil 231 and/or the projected portionor the deformed portion 233 a, 233 a of the side cores 233, 233, whichincrease the magnetic flux at the shoulder portion at the end of thesidewall portion 204 b than that at the center portion of the treadportion 204 a, it is possible to heat width direction of the green tire204 uniformly and to reduce the temperature irregularity. Also, in thecase where the thickness of the shoulder portion at the end of thesidewall portion 204 b is thicker than that of the center portion of thetread portion 204 a, such as a tire for RV vehicle or truck/bus, byfurther increasing the magnetic flux at the shoulder portion, it ispossible to heat the shoulder portion intensively than the centerportion of the tread portion 204 a.

Again referring to FIG. 15, a pair of the local preheating coils 213(second coil means) for the bead portion 204 c is disposed along thelower bead portion 4 c below and in the vicinity of the lower beadportion 204 c for applying an intensive high frequency magnetic field tothe bead wire 206 (metal member) of the lower bead portion 204 c, and isdisposed along the upper bead portion 4 c above and in the vicinity ofthe upper bead portion 204 c for applying an intensive high frequencymagnetic field to the bead wire 206 (metal member) of the upper beadportion 204 c. As shown in FIG. 17, the local preheating coil 213 forthe bead portion has a constitution that coil 235 is wound in a spiralshape facially and core 236 is positioned at one surface of the coil235.

The spiral coil 235 is constituted by the electric wire winding bundledwith a coil so as to surround around the center through portion. Here,the coil of which the electric wire winding is more than 60 mm and widthof the center through portion is about the same as the electric wirewinding. The electric wire winding has an elliptical shape and isdisposed so as to have long axis in the extending direction of the beadportion 204 c. The core 236 has an elongate shape extending along thelong axis of the elliptical coil 235 wound spirally and is exposed at ashort axis side of the coil 235. As shown in FIG. 17( b), the core 236has recesses 236 a, 236 a through which the coil 235 is passed. By meansof the elliptical coil 235 wound spirally and the elongate core 236having the recesses 236 a, 236 a, high frequency magnetic field isformed along the bead wire 206 embedded in the bead portion 204 c. Thecoil 235 may have a circular spiral shape and the core 236 may be acircular plate having a ring-shaped recess. Heating efficiency is higherin the case where the elliptical spiral coil 235 and elongate core 236are combined. Also, if the core 236 is not an integral body but is splitinto a center core 236 b, middle cores 236 c, 236 c, and side cores 236d, 236 d, then the magnetic flux density along the bead wire 206 isincreased and the bead wire 206 can be heated more efficiently.

In the above constitution, process of heating the green tire 204 will beexplained with reference to FIG. 15. The green tire 204 is movedhorizontally by a transporting apparatus (not shown) to be positionedabove the lower supporting plate 222, and then by lowering the uppersupporting plate 221 vertically, the green tire 204 is held between theupper and the lower supporting plate 221, 222. Next, the green tire 204rotates horizontally by the rotational driving apparatus (not shown) viathe rotating shaft 224, as well as the pressure fluid flows from thepressure fluid supplying source 226 into the green tire 204 via thepassage 225, thereby the green tire 204 is expanded to a predeterminedshape.

Next, the local preheating coil 212 for the tread portion 204 a (thefirst coil means) is advanced toward the green tire 204. At this time, aguiding means by the guide roller 215 is provided at both sides of thelocal preheating coil 212, and the distance between the local preheatingcoil 212 and the tread portion 204 a, i.e. the steel belt 205 ismaintained constant. Also, the local preheating coils 213, 213 (thesecond coil means) for the upper and the lower bead portions 204 c, 204c are advanced toward the green tire 204.

And, respective preheating coils 212, 213, 213 are supplied with highfrequency power from the high frequency power supply (not shown). Thelocal preheating coil 212 for the tread portion supplied with highfrequency power applies high frequency magnetic field to the treadportion 204 a with high magnetic flux density, to induction-heat thesteel belt 205 of the tread portion 204 a efficiently. Particularly,since high frequency magnetic field is formed in the plane of a widthdirection with respective to the metal steel belt 205 of the treadportion 204 a, a magnetic flux density passing through the metal steelbelt 205 becomes large and a circumferential direction of the steel belt205 of the tread portion 204 a is induction-heated efficiently.

Meanwhile, the local preheating coils 213, 213 for the bead portionapply high frequency magnetic field to the upper and the lower beadportions 204 c, 204 c with high magnetic flux density, respectively, toinduction-heat the bead wire 206 of the upper and the lower beadportions 204 c, 204 c efficiently. Particularly, in the case where thespiral local preheating coils 213, 213 are used, high frequency magneticfield is formed along the circumferential direction of the bead wire 206(metal member) of the upper and the lower bead portions 204 c, 204 c.Accordingly, by applying sufficient alternating magnetic field to thebead wire 206, the bead portions 204 c, 204 c having large thicknesswhere the temperature rising is delayed upon vulcanization, can bepreheated sufficiently.

Since the green tire 204 has rotated horizontally, the local preheatingcoil 212 for the tread portion 204 a and the local preheating coils 213,213 for the bead portions 204 c, 204 c become a state of movingrelatively along the green tire 204. Accordingly, even in the case thatthe local preheating coils 212, 213, 213 are not positioned correctlyand high frequency magnetic field is applied non-uniformly to the treadportion 204 a and the upper and the lower bead portions 204 c, 204 c ofthe green tire 204, it is possible to apply high frequency magneticfield for induction-heat uniformly over the whole green tire 204.Thereby, it is not necessary to assemble or process the preheating coils212, 213, 213 with high precision, and operations for assembling andprocessing can be facilitated.

As shown in FIG. 15, in this embodiment, before vulcanizing the greentire 204 having metal members embedded therein, such as aring-belt-shaped steel belt 205 or a wire-ring-shaped bead wire 206, thepreheating method of the green tire in which high frequency magneticfield for induction-heat is formed with high precision along the metalmembers, is performed, so that the inside of the green tire where thetemperature raising is mostly delayed upon vulcanization, is preheatedwhile it is heated, thereby it is possible to complete the vulcanizationin a short time. Specifically, at least one of the ring-belt-shapedsteel belt 205 and the wire-ring-shaped bead wire 206 (metal members)respectively embedded in the inside of tire, that is, the tread portion204 a and bead portions 204 c, 204 c are heated by induction, so thatparticularly the inside of tire, that is the tread portion 204 a and badportions 204 c, 204 c having large thickness is efficiently preheated,thereby the vulcanization can be completed more surely in a short time.

In this embodiment, although the case that the metal members areembedded in the tread portion 204 a and the bead portions 204 c, 204 cis explained, the present invention is not limited to this case, and canbe applied to the case that the metal member is embedded in an optionalportion having large thickness. Accordingly, for example, in the casewhere the metal members are embedded in the sidewall which become thesidewall portion, at least one of the metal member embedded in the treadportion 204 a, the bead portions 204 c, 204 c and the sidewalls may beinduction-heated.

In the green tire preheating apparatus 210, a moving means for rotatingthe green tire 204 is provided by the rotational driving apparatus thatis not shown, but the present invention is not limited to thisembodiment. Namely, the moving means may be a constitution comprising amoving means for relatively moving the local preheating coil in acircumferential direction of the green tire 204.

Also, in FIG. 15, the local preheating coil means 212 for the tread (thefirst coil means) is positioned between a pair of the green tires 204,204, and is formed to preheat them at the same time. However, it ispossible to preheat one green tire 204 using same local preheating coilmeans 212. At this time, if a ferrite core is disposed at the localpreheating coil means 212 side opposite to the green tire 204, amagnetic flux at the side opposite to the green tire 204 is concentratedso that the heating efficiency can be increased. The shape and disposingmethod of local preheating coil 212 for the tread portion 204 a in thegreen tire preheating heating apparatus 210 may be constituted as shownin FIGS. 16 to 26.

As shown in FIG. 18, by adding a deformed portion to a shape of thecenter core, heating of the shoulder portion 204 d can be promoted. InFIG. 18( a), the center core 241 has protruded portions 241 a, 241 aheading toward the green tire 204 side, at above and below thereof, andhigh frequency magnetic field in a width direction of the steel belt 205becomes high density near the shoulder portion 204 d. Also, in FIG. 18(b), in addition to the center core 241 having the protruded portions 241a, 241 a, that is, in addition to magnetic flux from the projectedportions 241 a, 241 a, auxiliary cores 242, 242 are installed to theshoulder portion 204 d. By means of the auxiliary cores, high frequencymagnetic field in a width direction of the steel belt 205 becomes higherdensity near the shoulder portion 204 d.

As shown in FIG. 19, the center core 243 has a thick portion 243 a and athin portion 243 b in a curved shape or stepped shape to be matched withR shape of the outer diameter of the green tire 204. By effectivelyusing the magnetic field formed by the coil 244 to increase the heatgeneration efficiency of the steel belt 205, the green tire 204 isheated efficiently.

As shown in FIG. 20, by adding the deformed portion to the shape of theside core, it is possible to promote the heating of the shoulder portion204 d, etc. A side core 233 shown in FIG. 20( a) has protruded portions233 a, 233 a heading toward the green tire similar to that explained inFIG. 16, but a side core 245 shown in FIG. 20( b) may have a protrudedportion 245 a, 245 a heading toward the circumferential direction of thegreen tire. As a side core 246 shown in FIG. 20( c), by having aprotruded portions 246 a heading toward the green tire 204 at the centerof a width direction, heating to the center portion of the tread portion204 a of the green tire 204 can be concentrated, similar to the shoulderportion 204 d. Also, as a side core 247 shown in FIG. 20( d), by forminga protruded portions 247 a only at the center of a width direction,heating to the center portion of the tread portion 204 a of the greentire 204 can be concentrated. As such, in the case where high frequencymagnetic field is corresponded in the surface direction of the steelbelt 205 of the green tire 204, by simply providing suitable protrudedportion in the side cores 233, 245, 246, 247, the heating level of thetread portion 204 a and the shoulder portion 204 d of the green tire 204can be adjusted.

Next, a local preheating coil 250 for the tread portion shown in FIG. 21will be explained in detail. A coil electric wire 250 a at the hollowcore portion is a shape of fin type, which is formed to a sector form tohave a large distance between each other. Thereby, heat radiation areaof the coil electric wire 250 a is increased so that heat generation dueto current from the coil electric wire 250 a can be reduced.

In the constitution shown in FIG. 22, high frequency magnetic field isformed in a circumferential direction of the green tire 204. A coilmeans 253 is formed, by arranging a rectangular core 252 wound with acoil 251 at a predetermined interval circumferentially. The windingdirections with respect to two cores 252 are reversed each other, andhigh frequency magnetic field heading in the circumferential directionof the green tire 204 is formed between two cores 252.

In FIG. 23, a coil means 254 is formed, by arranging a pair of cores 252shown in FIG. 22 at a predetermined interval in a width direction of thegreen tire 204. High frequency magnetic field heading in a widthdirection of the green tire 204 is formed between two cores 252. In FIG.24, a coil 255 to be wound around the core 205 shown in FIG. 23 has aspiral shape, and a coil means 256 is formed by making the windingdirections to be different at the upper and the lower cores 252. Highfrequency magnetic field heading in a width direction of the green tire204 is formed between two cores 252.

Also, in FIGS. 22 to 24, two coil units of the coil means 253, 254, 256can be disposed in the inclined direction between the circumferentialdirection and the width direction. Particularly, as shown in FIG. 7,since the metal wire of the steel belt 205 is disposed with an angle of10˜30° circumferentially, two coil units are disposed in this directionand high frequency magnetic field can be formed in the direction of themetal wire. Since the metal wire is disposed so as to intersect with anangle of ±10˜30° circumferentially, by disposing two sets of coil means253, 254, 256 having different directions at a predetermined intervalcircumferentially with respect to the green tire 204, high frequencymagnetic field can be perfectly corresponded in the circumferentialdirection of the metal wire of the steel belt 205.

A local preheating coil for the tread portion 204 a as shown in FIG. 25will be explained in detail. Center cores 261, 261 are split into theupper and the lower two cores, and a coil 262 is spirally wound aroundthe center cores 261, 261 in the same direction, respectively, and thentwo same coil units are arranged above and below in parallel. With theabove constitution, even in the case that size of the green tire 204changes and width of the metal member of the ring-belt-shaped steel belt205 changes, since by relatively moving the split coil units U1, U2 in awidth direction of the green tire 204, width of high frequency magneticfield heading in the circumferential direction of the green tire 204 canbe adjusted, work for exchanging the local preheating coil every timewhen the size of the green tire 204 is changed is unnecessary, and thegreen tire 204 can be induction-heated effectively.

FIG. 26 shows an example managing the other width adjustment of thelocal preheating coil of the tread portion 204 a. In FIG. 26( a), twocoil units U11, U12 are arranged in a width direction of the green tire204, and the distance between the coil units U11, U12 is adjustedcorresponding to the size change of the green tire 204. In FIG. 26( b),shape of the center core 262 is changed from that in FIG. 25 anddeformed toward the shoulder portion 204 d, so that although thevertical distance between the coils units is changed, concentration ofheating to the shoulder portion 204 d is not changed. In FIG. 26( c)shape of the center core 263 is deformed so as to be curved along theshoulder portion 204 d, so that although the vertical distance betweenthe coil units is changed, concentration of heating to the shoulderportion 204 d is not changed. FIG. 26( d) has three coil unitsconsisting of an upper, a center and a lower units, in which position ofthe center coil unit U21 is not changed, and by changing the distancebetween the upper or the lower coil unit U22, U23 and the center coilunit U21, although the position of the coil unit U22, U23 is changed dueto size change of the green tire 204, heating to the tread portion 204 ais not reduced by the coil unit U21.

Embodiments are not limited to above, and for example may be practicedby changing as described below.

(1) In FIG. 15, the local preheating coil 212 is not limited to only oneset for the green tire 204, and by disposing at least two sets of localpreheating coils 212 on the outer circumference of the green tire 204,it is possible to form high frequency magnetic field along almost of theouter circumference of the green tire 204. The set of local preheatingcoils 213, 213 for the bead portions is also not limited to only eachone set for the upper and the lower bead portions 204 c, 204 c, and atleast two sets of the local preheating coils 213, 213 for the beadportion can be disposed along the upper and the lower bead portions 204c. Also, by changing the number of coils such that the local preheatingcoils 212 for the tread is one set and the local preheating coils 213,213 for the bead portions are at least two sets, the preheating to thetread portion 204 a and the bead portions 204 c can be balanced. Also,in the case where the local preheating coil 212 is used exclusively forone green tire 204, it is preferred to concentrate the magnetic flux atthe opposite side by a ferrite core.

(2) Also, frequency of high frequency power supply to be applied tocoils of the local preheating coil 212 for the tread and the localpreheating coil 213 for the bead portion is properly selected in a rangeof 50 Hz˜100 kHz, preferably 10˜50 kHz. Since constitutions of the innersteel belt 205 and the bead 206 are different depending on the type orsize of the green tire 204, the frequency suitable for forming highfrequency magnetic field along the extending direction of the metalmember is selected in the above range.

In the above embodiments, the heating apparatus of the present inventionis explained mainly regarding to a preheating apparatus, but may beapplied to the vulcanizing apparatus by changing its shape suitably.

EXAMPLE

When the green tire was heated with electromagnetic induction-heating of30 kHz using the first coil means of FIG. 16, temperature rising curveat a center portion of the tread portion 204 a and a belt edge of theshoulder portion 204 d is shown in FIG. 27. Since the side core 233 ofthe coil means of FIG. 16 has the protruded portions 233 a, 233 a,temperature rising curve at the belt edge is above the temperaturerising curve at the center portion. If the side core 233 does not havethe protruded portions 233 a, 233 a, temperature rising curve at thebelt edge and the temperature rising curve at the center portion arereversed. As such, according to the extent of the protruded portions 233a, 233 a of the side core 233, the green tire 204 can be heateduniformly in a width direction.

When the green tire was heated with electromagnetic induction-heating of30 kHz using the second coil means of FIG. 17, temperature rising curveat a coil side of the bead portion 204 c and a tire side is shown inFIG. 28. It is found that heating of which temperature differencebetween the inside and the outside is small can be realized, even thoughthe wire-ring-shaped metal member may be used.

Although technical spirits of the present invention has been disclosedwith reference to the appended drawings and the preferred embodiments ofthe present invention corresponding to the drawings has been described,descriptions in the present specification are only for illustrativepurpose, not for limiting the present invention.

Also, those who are skilled in the art will appreciate that variousmodifications, additions and substitutions are possible withoutdeparting from the scope and spirit of the present invention. Therefore,it should be understood that the present invention is limited only tothe accompanying claims and the equivalents thereof, and includes theaforementioned modifications, additions and substitutions.

FIG. 1 keeping process forming process vulcanizing process highfrequency power supply FIG. 2 forming process keeping processvulcanizing process FIG. 3 vulcanizing process keeping process formingprocess transport a tire having completed the vulcanization to laterprocess transport a holding mechanism to a forming process FIG. 4 FIG. 5N₂ gas FIG. 6 high frequency power supply FIG. 7 FIG. 8(a) FIG. 8(b)FIG. 9(a) FIG. 9(b) FIG. 10(a) FIG. 10(b) high frequency power supplyFIG. 11(a) FIG. 11(b) high frequency power supply FIG. 12(a) FIG. 12(b)high frequency power supply FIG. 13(a) FIG. 13(b) driver voltagedetector inverter rectify- ing cir- cuit FIG. 14(a) FIG. 14(b) FIG.15(a) FIG. 15(b) FIG. 16(a) FIG. 16(b) FIG. 17(a) FIG. 17(b) FIG. 18(a)FIG. 18(b) FIG. 19 FIG. 20(a) FIG. 20(b) FIG. 20(c) FIG. 20(d) FIG. 21FIG. 22 FIG. 23 FIG. 24 FIG. 25 FIG. 26(a) FIG. 26(b) FIG. 26(c) FIG.26(d) FIG. 27 belt edge tread center FIG. 28 coil side tire side

1. An apparatus for heating a green tire by generating heat to a metalmember embedded in the green tire using electromagnetic induction,comprising: a heating coil for forming high frequency magnetic fieldalong a portion of an extending direction of said metal member; a highfrequency power supply for supplying high frequency power to saidheating coil, a magnetic material member for inducing a high frequencymagnetic field formed by said heating coil to said metal member, whereinsaid magnetic material member is positioned at an exterior side of thetire when the magnetic material member induces a high frequency magneticfield formed by said heating coil to said metal member; and means forproviding relative rotation for the green tire relative to the heatingcoil and magnetic material member, whereby the heating coil and magneticmaterial member rotate relative to said metal member.
 2. The apparatusfor heating a green tire according to claim 1, wherein the apparatus forheating is a preheating apparatus to be adapted to a preheating processbefore the green tire enters into a green tire vulcanizing apparatus. 3.The apparatus for heating a green tire according to claim 1, wherein theheating coil is disposed inside the green tire.